Education
Exercise selection criteria
Limiting factors, Lombard’s paradox, training at long lengths, load profile and stability.
1. Compound vs. isolation
A long debate asked whether heavy compounds alone build maximal mass or isolation is required. Neuromuscular science gives a clear, bifurcated answer.
Compound movements
- Advantages: maximal loads, large muscle mass per unit time, strong strength stimulus, time-efficient.
- Limitation: the set ends when the weakest link fails—not when the target muscle is fully overloaded. In bent-over rows, spinal erectors or grip often limit before the lats reach true failure.
Isolation movements
- Advantages: remove confounding weak links; direct ~100% of mechanical tension to one muscle bed.
- Limitations: low time efficiency for whole-body work; less integrated systemic and neural stimulus.
2. Bi-articulate muscle groups
Bi-articulate muscles cross two joints (rectus femoris, hamstrings, long-head triceps, biceps). In compounds they often work inefficiently—Lombard’s paradox.
Hamstrings and rectus femoris in squats
Squats demand knee and hip extension together. The rectus femoris shortens at the knee but lengthens at the hip; hamstrings do the reverse. Fiber length stays nearly constant—quasi-isometric, weak hypertrophy signal. Squats grow quads and glutes well but hamstrings poorly—isolate with seated or prone leg curls.
Long-head triceps in pressing
Pressing extends the elbow (triceps shorten) while flexing the shoulder (long head lengthens). Flat bench underloads the long head—use overhead or flexed-shoulder extensions.
3. Training at long muscle lengths
Mechanism
Heavy loading in a lengthened state combines active tension (actin–myosin) with passive tension from titin. The combined mTOR-related signal exceeds loading mainly in shortened positions.
Exercise selection
- Glutes: Romanian deadlifts and deep squats (peak torque when lengthened) beat glute bridges (peak in lockout/shortening).
- Biceps: incline or preacher curls (max shoulder-extension stretch) beat standing barbell curls.
4. Henselmans selection criteria
Resistance vs. strength profile
The resistance curve should match the joint torque curve: hardest where the muscle is strongest, lighter where it is disadvantaged.
Freedom of movement
Fixed tracks (Smith machine) force unnatural joint paths and chronic connective-tissue stress. Free weights and cables let anatomy self-select the path.
Stability
Higher stability frees prefrontal and stabilizer demand—more neural drive to the target pool. A stable leg press can overload quads more than squats on an unstable surface.